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  • (Score: 2) by The Shire on Saturday November 24 2018, @06:23PM (7 children)

    by The Shire (5824) on Saturday November 24 2018, @06:23PM (#765940)

    I don't think folks realize just how much tech would never exist without the crystal oscillator. Radios, computers, even the oscilloscopes and counters we rely on to develop modern technology all rely on crystal oscillators. If this property of crystals did not exist then we'd still be in the 19th century.

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  • (Score: 3, Touché) by fyngyrz on Monday November 26 2018, @09:15PM (6 children)

    by fyngyrz (6567) on Monday November 26 2018, @09:15PM (#766613) Journal

    If this property of crystals did not exist then we'd still be in the 19th century.

    The L/C circuit wants a (moderately stable) word with you.

    • (Score: 2) by The Shire on Tuesday December 04 2018, @11:43AM (5 children)

      by The Shire (5824) on Tuesday December 04 2018, @11:43AM (#769498)

      The LC is the poor mans crystal oscillator. It uses more power, is less precise, and drifts with both time and temperature.

      Millions of kids were inspired to get into electronics when, to their amazement, they could build a crystal set radio that required no power other than the unseen electromagnetic waves from the radio transmission tower. If you tried to make something like that with an LC circuit, well, you can't.

      Maybe I'm just showing my age, but I'm one of those kids who was inspired by the crystal set radio.

      • (Score: 3, Informative) by fyngyrz on Tuesday December 04 2018, @06:32PM (4 children)

        by fyngyrz (6567) on Tuesday December 04 2018, @06:32PM (#769690) Journal

        If you tried to make something [that requires no power other than the unseen electromagnetic waves from the radio transmission tower] with an LC circuit, well, you can't.

        Sure you can. An inductive antenna picks up energy just fine. Get enough, tune the circuit for the AM BCB frequency you want, and you'll be able to rectify, filter, and use the result. All you need is a diode, a resistor, and a cap in addition to the LC circuits. Bingo, you have a radio receiver.

        [an LC circuit] uses more power, is less precise, and drifts with both time and temperature.

        Cystals offer a reasonably high inherent level of stability, this is true. Although adding temperature regulation helps. As it does with LC circuits, in fact. However, stability isn't always required to generate clocks, and clocks are the heart of a great deal of digital circuitry. Other digital circuits just run in realtime, no clock required (see your typical AND, OR, XOR, NOT, etc.)

        Crystals also drift with time and temperature. They just drift a lot less. But again, both can be significantly stabilized by stabilizing their environment. You can transmit and receive with nothing to determine frequency but LC-based circuitry. Ham radio operators still do that on a regular basis, BTW.

        PS: I design radio systems, using software and both digital and analog circuitry. This is my ballpark.

        • (Score: 0) by Anonymous Coward on Wednesday December 05 2018, @10:49AM (1 child)

          by Anonymous Coward on Wednesday December 05 2018, @10:49AM (#770019)

          OTN IDNNT YCU the <abbr> tag OTS. ITNF?

          • (Score: 2) by fyngyrz on Wednesday December 05 2018, @02:30PM

            by fyngyrz (6567) on Wednesday December 05 2018, @02:30PM (#770077) Journal

            is that new functionality?

            I don't know if it's new. It might be. The tag came to my notice when I suggested a means to process TFSs such that common "mystery" terms were automatically, and non-invasively, expanded.

            Having been informed, I wrote this webapp [github.com] to take advantage of it, and to try to encourage the powers-that-be here to use this mechanism in TFSs.

            That's what I'm using to get <abbr> into my posts.

        • (Score: 2) by The Shire on Wednesday December 05 2018, @12:32PM (1 child)

          by The Shire (5824) on Wednesday December 05 2018, @12:32PM (#770042)

          I would expect an antenna capable of providing the requisite power for an LC circuit would be a tad more elaborate than what's needed for a crystal wouldn't it? That being said, I didn't realize they had such low power requirements such that they could be driven over the air like that. That's pretty neat.

          Anyway, maybe it's just personal bias, but I still maintain that the good old crystal set launched the career of many an electrical engineer. I know it amazed me when I was a little kid. The thing was practically magical.

          • (Score: 2) by fyngyrz on Wednesday December 05 2018, @02:23PM

            by fyngyrz (6567) on Wednesday December 05 2018, @02:23PM (#770073) Journal

            I would expect an antenna capable of providing the requisite power for an LC circuit would be a tad more elaborate than what's needed for a crystal wouldn't it?

            No. A crystal radio works the same way. The first LC circuit is the antenna and (usually) a capacitor; that collects the energy over a specific frequency range, and all the crystal does is rectify it; it performs the function of a diode.

            A capacitor (in early sets, this could be inherent in the wires or the earphones themselves) then changes it from uni-polarity RF pulses to a more-or-less smoothed audio signal.

            In a modern radio, the semiconductor diode does the rectification, so the crystal is no longer needed. There are diodes (ex. germanium, schottky) with much lower forward voltages (and much higher reverse voltages) than your typical iron pyrite or galena crystal + whisker; this means that a diode-and-LC based replacement for a crystal radio can capture smaller signals, and survive larger ones, such as static discharges.

            Anyway, maybe it's just personal bias, but I still maintain that the good old crystal set launched the career of many an electrical engineer. I know it amazed me when I was a little kid. The thing was practically magical.

            I think you're absolutely right on that one.